A technology for detecting a collision between a vehicle and a pedestrian is disclosed in each of Patent Documents 1 and 2 shown below. In such a technology for detecting a vehicle-pedestrian collision, what is important is to recognize whether or not an object colliding with a vehicle is a pedestrian.
In Patent Document 1 of a patent owned by the present applicant, it is disclosed to perform the recognition of a pedestrian based on both of a collision load and a collision width. Specifically, to detect the collision width, a large number of pressure sensors are arranged in a bumper in a longitudinal direction thereof. By regarding the total sum of collision loads detected by the respective pressure sensors as a collision load resulting from a collision object, a collision mass is calculated from the collision load and from a vehicle velocity measured by a vehicle velocity sensor. In addition, the width of the collision object (referred to as the collision width) is calculated from the total width of the pressure sensors in each of which the collision load (or collision mass) exceeds a predetermined threshold value. When the calculated width falls within a predetermined range, a collision with a pedestrian is recognized.
On the other hand, Patent Document 2 discloses recognition of a pedestrian from the detected collision width.
Patent Document 1: JP-2005-053473 A (corresponding to US2005/0021192)
Patent Document 2: EP No. 1710131
When the collision object is only one pedestrian, there is no problem in detecting the width of a pedestrian by either of the methods of Patent Documents 1, 2 shown above. However, a case may be assumed in which a vehicle collides with multiple pedestrians generally at the same time. In such a case, since the detected width of the collision objects exceeds the preset assumed width of a pedestrian, it is impossible to recognize that the collision objects are pedestrians. As a result, the drawback has been found that an erroneous determination may be made.